Ghostly Skull x/x/2 (or second UV with Unholy Ascension)
Unborn Val'kyr x/2/1
Blighted Squirrel 2/x/2 (can be Infected Squirrel 2/2/2 if your Val'kyr is H/H)
1. Pass – your Unborn Val'kyr is forced in
2. Swap back to Ghostly Skull
3. Unholy Ascension
4. Pass – your Unborn Val'kyr is forced in
5. Curse of Doom
7. Woodchipper (or Creeping Fungus)
If using a 2nd UbV in slot 1, it has to be H/H breed. The B/B has 244sp and when Mar'cuus uses Prowl, its sp drops to 243 making Unholy Ascension go first and messing up the strat.
All 3 breeds of Ghostly Skull are fine, however.